This invention relates to a multiplex broadcasting method and system for broadcasting main broadcasting information together with predetermined sub broadcasting information multiplexed with the main broadcasting information such as, for example, character multiplex broadcasting as well as a receiving apparatus for the broadcast.
Character multiplex broadcasting is conventionally known wherein image information constituted from characters and/or graphic forms is multiplexed in a digital signal with a television signal and sent out and the signal is decoded and displayed on a television receiver on the receiving side.
On the sending out side, additional sound is combined in accordance with the necessity with a screen including characters and/or a graphic form or forms to produce a character broadcasting screen. Each such character broadcasting screen is coded, and data designating a program number, a page number, a display mode and so forth are added to the coded character broadcasting screen.
A synchronizing code, an error correction code and so forth are further added to form a character signal, and the character signal is transmitted in a superimposed relationship in the 14th H (H denotes a horizontal section) to 16th H and the 21th H in a vertical blanking period.
On the receiving side, the character signal is separated from a demodulated video signal, and the character broadcasting data are decoded after error correction processing of the character signal. In accordance with the data, a pattern data or a graphic data read out from a ROM is written into a display memory, converted into a video signal and displayed on an image receiving tube.
It is to be noted that the image information may be printed as a hard copy by a printer.
Further, electronic sound is reproduced from a loudspeaker in response to the additional sound data.
In a character multiplex broadcast, data lines of the hierarchy 2 superimposed in one horizontal scanning period are divided into a synchronizing section of 24 bits and a data packet (hierarchy 3) of 272 bits.
Program data of the hierarchy 5 include, as shown in FIG. 6, program management data and individual page data, and a program data header includes a number for identification of the program and another number for identification of a group of programs.
It is to be noted that, as the related art, it is disclosed in U.S. Pat. No. 4,706,121 that program information is superimposed with a V-BLK of a television broadcasting signal and a video tape recorder is controlled in accordance with the thus superimposed signal.
By the way, conventionally in a private television broadcast (ground wave) or a broadcast based on a communications satellite (CS), when a commercial message (CM) is broadcast, since it is broadcast by way of an ordinary image and sound, naturally the entire service area SA (at least the area of a district or the entire country) of the broadcasting station makes an object area ZCM of the commercial message broadcasting as seen in FIG. 7.
Meanwhile, in CATV systems of the multi-channel type which have increased suddenly in recent years, a television broadcasting program of a ground wave of a VHF or UHF is re-transmitted by way of a transmission medium such as a coaxial cable and a sustaining program distributed by way of a communications satellite is transmitted in a mid band or a super high band to distribute such programs to a great number of subscribers. However, a commercial message is broadcast in the area of a district or the entire country similarly as in an ordinary television broadcast.
Consequently, there is a problem in that the advertising rates by a conventional television broadcast are naturally so high that, for example, a small or medium enterprise of the type which is closely related to a district cannot make use of an advertisement by television broadcasting even if it is broadcast only within the district since the economical burden to the enterprise is excessively high.
Further, in a conventional television broadcast, for example, information relating to a district such as, for example, weather information or road information is successively broadcast in the scale of the entire country or the district. Accordingly, a conventional television broadcast cannot provide detailed information which are different among different districts.